title: Structural determinants of the cellular localization and shuttling of TDP-43.
abstract: TDP-43 (also known as TARDBP) regulates different processes of gene expression, including transcription and splicing, through RNA and DNA binding. Moreover, recent reports have shown that the protein interacts with the 3'UTRs of specific mRNAs. The aberrant cellular distribution and aggregation of TDP-43 were recently reported in neurodegenerative diseases, namely frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). A detailed description of the determinants for cellular localization has yet to emerge, including information on how the known functions of TDP-43 and cellular targeting affect each other. We provide the first experimental evidence that TDP-43 continuously shuttles between nucleus and cytoplasm in a transcription-dependent manner. Furthermore, we investigate the role of the functional TDP-43 domains in determining cellular targeting through a combination of immunofluorescence and biochemical fractionation methods. Our analyses indicate that the C-terminus is essential for solubility and cellular localization, because its deletion results in the formation of large nuclear and cytoplasmic aggregates. Disruption of the RNA-recognition domain required for RNA and DNA binding, however, alters nuclear distribution by decreasing TDP-43 presence in the nucleoplasm. Our findings suggest that TDP-43 solubility and localization are particularly sensitive to disruptions that extend beyond the newly found nuclear localization signal and depend on a combination of factors that are closely connected to the functional properties of this protein.
authors.affiliation: International Centre for Genetic Engineering and Biotechnology (ICGEB), 34012 Trieste, Italy.
authors.forename: Youhna M
authors.initials: YM
authors.lastname: Ayala
authors.forename: Paola
authors.initials: P
authors.lastname: Zago
authors.forename: Andrea
authors.initials: A
authors.lastname: D'Ambrogio
authors.forename: Ya-Fei
authors.initials: YF
authors.lastname: Xu
authors.forename: Leonard
authors.initials: L
authors.lastname: Petrucelli
authors.forename: Emanuele
authors.initials: E
authors.lastname: Buratti
authors.forename: Francisco E
authors.initials: FE
authors.lastname: Baralle
mesh_terms: D020816:Amino Acid Motifs; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D019913:Nuclear Localization Signals / Q000235:genetics; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017384:Sequence Deletion
chemical_list: D004268:DNA-Binding Proteins; D019913:Nuclear Localization Signals